In current wireless network scenarios, a device will typically communicate with a network infrastructure node such as a base station or an access point that the device is being served by, which will then allow communication to other devices, including those served by that same network infrastructure node, or to devices served by other network infrastructure nodes. However, such communication may not be possible in certain areas where wireless network coverage from an infrastructure node does not exist, for example, remote areas without wireless network deployment or areas which have suffered a destruction of wireless network infrastructure. Further, even where wireless network coverage exists, communications using a network infrastructure node may not be desirable. For example, in general communication systems, a direct D2D transmission of data may provide more efficient utilization of radio resources than current networks.
Device-to-device communications are communications between two wireless devices or user equipments (UEs), where the communication proceeds directly between UEs and does not proceed through a network infrastructure node. Uses for D2D communications may be for both emergency and non-emergency situations. For example, first responders and public safety members may use D2D communications to communicate between devices. This may be useful in situations where there is no network coverage, such as remote areas or inside a building. However, even in network coverage areas, in some cases D2D communications are desirable in public safety situations.
In non-emergency situations, friends that are in close proximity to each other may wish to communicate directly with each other. Other cases include human-to-machine interaction, such as parking meters talking to mobile wireless devices within range to help a user of a mobile wireless device find a free parking space. Machine-to-machine communication is possible as well, for example, temperature/humidity/pressure sensor communicates recorded data to a controller device. Other examples are possible. The devices involved may be stationary or mobile.
The operation of a device for communicating with other devices without a network infrastructure element however has challenges, since there is no central control for such communications.